Sheet conveyance apparatus and image reading apparatus

ABSTRACT

A sheet conveyance apparatus includes a conveyance roller which conveys a sheet and an elastic guide member one end of which is fixed and supported, the other end of which faces the conveyance roller as a free end, and which can be elastically transformed. The conveyed sheet is sandwiched between the conveyance roller and the elastic guide member, and the elastic guide member is elastically transformed to bring the sheet into press contact with the conveyance roller.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a sheet conveyance apparatus which coneys a sheet and an image reading apparatus which conveys an original document serving as a sheet to read image information recorded on the original document.

2. Description of the Related Art

FIG. 8 is a sectional view schematically showing an example of a sheet conveyance apparatus which reads image information on an original document 1 while conveying the original document 1 serving as a sheet to perform printing or the like in an image forming apparatus such as a copying machine or a facsimile machine. The sheet conveyance apparatus is singularly used as an image reading apparatus or arranged so as to be built in an image forming apparatus main body.

The original document 1 is sent out from an original base plate by a pickup roller 2 and taken into the apparatus by a sheet feeding roller 3. When the sheet is taken into the apparatus by the sheet feeding roller 3, in order to prevent a plurality of original documents 1 from overlapping and being taken at once, namely, in order to prevent so-called double feeding, the original documents 1 are separately fed one by one by a separating roller 4. The original document 1 is sandwiched and further conveyed by one pair of opposing registration rollers 5 facing a conveyance path and caused to pass through one pair of opposing image sensors 6. Pieces of image information recorded on both the front and rear sides of the original document 1 are scanned and read. The read original document 1 is further conveyed to one pair of opposing registration rollers 7. Thereafter, in this case, a switching lever 8 can switch the original document 1 to any one of a conveyance path on which conveyance is performed by feeding the original document 1 to a U-shaped path 11 or a conveyance path on which conveyance is performed by feeding the original document 1 to a straight path (not shown).

In the U-shaped path 11, one pair of guide rollers 9 a and 9 b are arranged opposite to each other while facing a curved path and sandwich the original document 1 to guide U-turn conveyance. One pair of opposing discharge rollers 10 a and 10 b are arranged on the downstream-side end of the U-shaped path 11, so that the original document 1 is discharged onto the upper portion of the apparatus. When the original document 1 is fed to the straight path by switching the switching lever 8, the original document 1 directly goes straight out of the registration rollers 7 and is discharged out of the apparatus.

On the other hand, as another example of the sheet conveyance apparatus, a recording medium conveyance apparatus in which a plurality of pressure rollers are aligned in a line at intervals, and one long conveyance roller is arranged in parallel to each rotating axes of the pressure rollers, so that a sheet serving as a recording medium is sandwiched between the pressure rollers and the conveyance roller to convey the sheet is known (see Japanese Patent Application Laid-open No. 10-181929). In this case, the pressure rollers arranged in the line are supported by holders, respectively. The pressure roller is biased to be pressed against the conveyance roller by a coil spring through the holders. In this manner, the pressure rollers are brought into press contact with the conveyance roller to obtain an appropriate surface compaction.

In the sheet conveyance apparatus shown in FIG. 8, in order to correctly guide the original document 1 with the curved portion of the U-shaped path 11, one pair of opposing guide rollers 9 a and 9 b and one pair of opposing discharge rollers 10 a and 10 b are arranged. For this reason, since the guide roller 9 b and the discharge roller 10 b arranged outside the curved portion of the U-shaped path 11 project outside, a dimension L2 represented by reference numeral L2 in FIG. 8 increases by the projecting portions. As a result, the housing of the apparatus main body increases in size disadvantageously.

In order to avoid this drawback, as shown in FIGS. 9A to 9C, the e in size of the apparatus can be suppressed as the roller diameters of the guide rollers 9 and the discharge rollers 10 decrease. However, when the roller diameters decrease, impact caused by the original document 1 is large when the original document 1 is inserted between the rollers. As a result, a paper jam easily occurs. The paper jam becomes conspicuous as the thickness of the original document 1 increases. For the above circumstances, there is a limit to reduce the guide rollers 9 or the discharge rollers 10 in size. Furthermore, a desired contact pressure must be always applied between the opposing rollers, and roller rotational loads increase. Accordingly, the rated powers of the motors must be disadvantageously matched to the roller rotational loads.

On the other hand, the recording medium conveyance apparatus disclosed in Japanese Patent Application Laid-open No. 10-181929 is constituted by a very large number of members such as the plurality of coaxial pressure rollers, the holding holders therefor, the biasing coil springs, and the opposite conveyance roller cooperated with the pressure rollers. Therefore, the large number of parts disadvantageously increase manufacturing cost including parts cost and assembly cost.

SUMMARY OF THE INVENTION

Therefore, it is a main object of the present invention to provide a sheet conveyance apparatus which can suppress the apparatus from increasing in size and can reduce the number of parts to make it possible to realize a reduction in cost. Furthermore, it is another object of the present invention to provide a sheet conveyance apparatus which can also effectively prevent paper jam of an original document or the like and which can contribute to an improvement in processing ability of an image forming apparatus when the sheet conveyance apparatus is installed in the image forming apparatus.

In order to achieve the above object, a typical sheet conveyance apparatus according to the present invention has the follows: a conveyance roller which conveys a sheet; and an elastic guide member one end of which is fixedly supported, the other end of which faces the conveyance roller as a free end, and which can be elastically transformed, and wherein the conveyed sheet is sandwiched between the conveyance roller and the elastic guide member, and the elastic guide member is elastically transformed to bring the sheet into press contact with the conveyance roller.

In a conventional conveyance apparatus, a conveyance roller which conveys a sheet is provided apparatus is strictly restricted by a parts storage space, a large space is occupied by the two rollers. For this reason, in the present invention of the application, one of two opposing conveyance rollers is caused to function in place of an elastic guide member. The space occupied by the elastic guide member becomes smaller than the projection of the roller main body of the conveyance roller. The sheet is fed between the elastic guide member and the conveyance roller. The elastic guide member is elastically transformed by contact force generated when the sheet is fed to escape to the opposite side together with the conveyance roller. The elastic guide member having appropriate elastic reactive force cooperates with the conveyance roller so as to be in press contact with the sheet.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an original document conveyance apparatus serving as a first embodiment of a sheet conveyance apparatus according to the present invention.

FIG. 2 is a perspective view showing a conveyance guide unit according to the embodiment.

FIG. 3A is a pattern diagram showing a mode obtained a sheet is fed into the conveyance guide unit.

FIG. 3B is a pattern diagram showing a mode obtained when the sheet is being fed into the conveyance guide unit.

FIG. 4 is a perspective view showing a second embodiment.

FIG. 5 is a diagram showing an original document conveyance apparatus according to a third embodiment.

FIG. 6 is a perspective view showing a conveyance guide unit according to the third embodiment.

FIG. 7 is a perspective view showing a conveyance guide unit according to a fourth embodiment.

FIG. 8 is a diagram showing a conventional original document conveyance apparatus.

FIG. 9A is diagram for explaining a problem of the conventional original document conveyance apparatus.

FIG. 9B is diagram for explaining a problem of the conventional original document conveyance apparatus.

FIG. 9C is diagram for explaining a problem of the conventional original document conveyance apparatus.

DESCRIPTION OF THE EMBODIMENTS

An original document conveyance apparatus serving as an embodiment of a sheet conveyance apparatus according to the present invention and an embodiment of an image forming apparatus including the original document conveyance apparatus will be described below in detail with reference to the drawings. The same reference numerals as in the sheet conveyance apparatus shown in FIG. 8 denote the same parts and the same members in the embodiments, and new reference numerals are add to main members as shown in the drawings subsequent to FIG. 1 to make major points of the embodiments more clear.

Sheet Conveyance Apparatus—First Embodiment

As shown in FIG. 1, in the original document conveyance apparatus according to the embodiment, an original document (sheet) 1 sent out from an original base plate by a pickup roller 2 is taken into the apparatus by a sheet feeding roller 3. At this time, in order to prevent a plurality of original documents 1 from overlapping and being picked up at once, namely, in order to prevent so-called double feeding, the original documents 1 are separated and detached from each other one by one by a separating roller 4. The original document 1 is sandwiched and conveyed by one pair of opposing registration rollers 5. Furthermore, pieces of image information recorded on both the front and rear sides of the original document 1 are scanned and read by one pair of opposing image sensors 6. The read original document 1 from which the pieces of image information are read is further conveyed to one pair of opposing registration rollers 7. Thereafter, the original document 1 can be switched by a switching lever 8 to any one of a conveyance path on which conveyance is performed by feeding the original document 1 to a U-shaped path 11 or a conveyance path on which conveyance is performed by feeding the original document 1 to a straight path (not shown). On the U-shaped path 11, a conveyance guide unit according to the embodiment is arranged so as to sandwich the curved portion of the U-shaped path 11 to guide conveyance travel of the original document 1. The original document 1 sent out from the conveyance guide unit is discharged onto the upper portion of the apparatus by discharge rollers 10. When the original document 1 is fed to the straight path by switching the switching lever 8, the original document 1 directly goes straight out of the registration rollers 7 and is discharged out of the apparatus.

In the conveyance guide unit, like a conventional conveyance roller, one conveyance roller 9 is arranged inside of a curved portion to face a curved portion formed such that a conveyance path is U-shaped, and an elastic guide member 20 molded in the form of a band by an elastic material such as a metal, a resin or the like is arranged outside the curved portion to face the conveyance roller 9. The conveyance roller 9 is constituted by a roller main body 9 d having an outer peripheral surface being in contact with the original document and a roller rotating shaft 9 c. As is apparent from FIG. 2, the conveyance roller 9 is arranged such that the roller rotating shaft 9 c orthogonally crosses a sheet conveyance direction (arrow A). Two elastic guide members 20 are arranged at such positions that the elastic guide members 20 do not interfere with both the ends of the roller main body of the conveyance roller 9. More specifically, the conveyance guide unit according to the embodiment is constituted by one conveyance roller 9 and two elastic guide members 20 on both the sides of the conveyance roller 9. Each of the elastic guide members 20 has a band-like shape one end of which is a fixed end 21 supported by an apparatus main body housing or the like (not shown) through a bracket and the other end of which is an elastically flexible free end 22.

As shown in FIGS. 3A and 3B, the original document 1 sent from the registration rollers 7 is conveyed to the U-shaped path 11 by a switching operation by the switching lever 8 and goes to the curved portion (see FIG. 3A). The free end 22 of the elastic guide member 20 is elastically bent by contact force of the original document 1 inserted between the conveyance roller 9 to escape to an outside indicated by an arrow in FIG. 3B.

As is apparent from FIG. 3A, the free end 22 of the elastic guide member 20 is set in an ordinary state in which the free end 22 is slightly bent inward from the surface level of the roller main body 9 d of the conveyance roller 9 and overlaps the roller main body 9 d without interfering therewith. More specifically, the elastic guide member 20 is not brought into contact with the outer peripheral surface of the roller main body 9 d. A part of the elastic guide member 20 is located closer to the roller rotating shaft 9 c than a virtual surface obtained by extending the outer peripheral surface of the roller main body 9 d in the axial direction of the conveyance roller 9. The original document 1 is interposed between the free end 22 of the elastic guide member 20 and the conveyance roller 9 to escape to the outside by elastically transforming the free end 22. Therefore, the conveyed sheet is sandwiched between the conveyance roller 9 and the plurality of elastically transformed elastic guide member 20. The original document is brought into press contact with the outer peripheral surface of the roller main body 9 d by elastic force of the elastic guide member 20.

In this case, the free end of the elastic guide member is set in an ordinary state in which the free end is bent inward from the surface level of the roller main body 9 d without interfering with both the ends of the roller main body 9 d of the conveyance roller 9. This is because the free end 22 is slightly overlapped on the conveyance roller 9 to effectively apply appropriate press-contact force to an area of the original document 1, which is longer and wider than an area obtained when both the members are in point contact with each other at a surface without being overlapped, depending on the thickness of the original document 1 in cooperation with the roller main body 9 d.

Even though impact generated when the original document 1 sent between the conveyance roller 9 and the elastic guide members 20 is considerably large, the free end 22 of the elastic guide member 20 is elastically bent to escape outside. For this reason, the original document 1 can be effectively prevented from being jammed. At this time, while the original document 1 is sent between the conveyance roller 9 and the elastic guide members 20, the elastic guide members 20 is appropriately elastically transformed to absorb press-contact force received by the roller main body 9 d, so that the press-contact force is not excessive. When the original document 1 is not sent between both the members, the elastic guide members 20 do not interfere with the conveyance roller 9. For this reason, the press-contact force received by the conveyance roller 9 is nothing. Regardless of the presence/absence of the original document, unlike in a conventional technique, a motor output need not be set to be large.

When the number of members in the apparatus according to the embodiment is compared with the number of members in the apparatus disclosed in Japanese Patent Application Laid-open No. 10-181929, one elastic guide member 20 functions as a biasing spring and a roller holding holder disclosed in Japanese Patent Application Laid-open No. 10-181929. For this reason, the number of members can be considerably reduced, and the cost can be reduced accordingly. According to the sheet conveyance apparatus according to the embodiment, one of two opposing conveyance rollers is omitted, and the remaining conveyance roller is caused to function in place of a band-like flat elastic guide member to reduce a space of one conveyance roller, so that the apparatus can be suppressed from being increased in size.

Sheet Conveyance Apparatus—Second Embodiment

FIG. 4 shows a second embodiment of the present invention which is also called a modification of the first embodiment. In the embodiment, when a combination of a conveyance roller and an elastic guide member is defined as one conveyance guide unit, a plurality of conveyance guide units are aligned in a direction orthogonally crossing a conveyance direction. More specifically, a structure in which two conveyance guide units each constituted by one conveyance roller 9 and two elastic guide members 20 are horizontally arranged, namely, arranged in a direction orthogonally crossing a sheet conveyance direction A is formed. In this manner, when the two conveyance guide units are horizontally arranged and used, the conveyance guide units can be in contact with the original document 1 in a wide area to effectively improve the conveyability of the original document. Shafts 9 c of the two conveyance rollers 9 are common.

As the first and second embodiments described above, the conveyance guide unit has an structure in which one of the outside of the conventional opposing two conveyance roller 9 (see FIG. 8) is caused to function as a roller in place of the bonded-like elastic guide member 20. Therefore a fixed size L1 of the overall apparatus can be reduced compound to a fixed size L2 to efficiently suppress the increase in size of the apparatus.

Sheet Conveyance Apparatus—Third Embodiment

FIGS. 5 and 6 show a third embodiment according to the present invention. In this embodiment, in order to give a compact low-conveyance-load structure to the original document conveyance mechanism described in the first embodiment in FIG. 1, external one of two opposing discharge rollers 10 is omitted, and the remaining discharge roller 10 is built in a structure as a part of a conveyance guide unit. When two conveyance rollers are arranged on upstream and downstream sides, an elastic guide member is fixed and supported at the center of the band-like shape, and free ends at both the ends of the elastic guide member are caused to face the upstream and downstream sides of the conveyance 10026088 rollers. More specifically, in this case, both the ends of an elastic guide member 30 serve as elastically flexible free ends 31 a and 31 b. The free end 31 a on one end side is a part cooperated with the conveyance roller 9, and the free end 31 b on the other end side is a part cooperated with the discharge roller 10.

In the third embodiment, a fixed size L1 of the overall apparatus can be reduced, and the external discharge roller 10 is omitted, so that a fixed size H of the overall apparatus in the height direction can be reduced.

In this case, a total of four elastic guide members 30 for the two conveyance guide units are arranged. However, the elastic guide members 30 are connected and coupled to each other at the respective central portions by a connection 32 having a long bar shape to form a single-piece product, so that assembling property of the apparatus is dramatically improved.

Sheet Conveyance Apparatus—Fourth Embodiment

In the first to third embodiments, one conveyance guide unit is constituted by two elastic guide members 20 on both the sides of one conveyance roller 9. However, as shown in FIG. 7, when one conveyance roller 9 is constituted by two divided rollers 9 a and 9 b, as a matter of course, the major point of the present invention can be applied.

(Image Reading Apparatus and Image Forming Apparatus)

On the other hand, when the sheet conveyance apparatus according to each of the embodiments is built in an image reading apparatus and equipped, a compact space-saving image reading apparatus which transmits image information of an original document scanned by a sheet conveyance apparatus to an external information processing machine can be realized. When the sheet conveyance apparatus according to each of the embodiments is built in a copying machine or a facsimile machine and equipped, image information scanned by the sheet conveyance apparatus is received and printed out by an image forming unit. More specifically, when a sheet is, for example, an original document, image information recorded on the original document is loaded on the sheet conveyance apparatus, and an image is formed by the image forming unit based on the loaded image information, printed out, subjected to other processes. In addition, when the sheet conveyance apparatus is built in a printer, a compact space-saving image forming apparatus which prints image information on a print sheet or the like conveyed by the sheet conveyance apparatus according to the present invention is realized.

A combination of a conveyance roller and an elastic guide member in the sheet conveyance apparatus has a minimum number of members, and the combination can be fitted into a limited member space in the main bodies of the image reading apparatus and the image forming apparatus. Therefore, the number of parts in the sheet conveyance apparatus is suppressed to make it possible to simplify the structure. The sheet conveyance apparatus can contribute to effective utilization of a member storage space of the image forming apparatus main body to also suppress paper jam of an original correlatively to the simplification of the structure of the sheet conveyance apparatus. For this reason, the overall processing ability of the image reading apparatus and the image forming apparatus can be assured advantageously.

The sheet conveyance apparatuses according to the first to fourth embodiments and the embodiment of the image forming apparatus equipped with the sheet conveyance apparatuses are explained. However, the present invention is not limited to these embodiments without departing from the spirit and scope of the invention, and other embodiments, combinations thereof, and applications can be applied.

This application claims the benefit of priority from the prior Japanese Patent Application No. 2005-031440 filed on Feb. 8, 2005 the entire contents of which are incorporated by reference herein. 

1. A sheet conveyance apparatus comprising: a conveyance roller which conveys a sheet; and an elastic guide member one end of which is fixed and supported, the other end of which faces the conveyance roller as a free end, and which can be elastically transformed, and wherein the conveyed sheet is sandwiched between the conveyance roller and the elastic guide member, and the elastic guide member is elastically transformed to bring the sheet into press contact with the conveyance roller.
 2. The sheet conveyance apparatus according to claim 1, comprising a conveyance path through which the sheet conveyed by the conveyance roller passes, wherein the conveyance path has a curved portion to have a U shape, and the conveyance roller is arranged inside the curved portion, and the elastic guide member is arranged outside the curved portion.
 3. The sheet conveyance apparatus according to claim 1, wherein the conveyance roller has a shaft and a roller main body having an outer peripheral surface which are in contact with the sheet, the plurality of elastic guide members are arranged on both the sides of the roller main body; the elastic guide members are not in contact with the outer peripheral surface of the roller main body, and a part of the elastic guide member is located closer to the shaft than a virtual surface obtained by extending the outer peripheral surface of the roller main body in an axial direction of the conveyance roller.
 4. The sheet conveyance apparatus according to claim 1, wherein when one conveyance guide unit is used as a combination of the conveyance roller and the elastic guide member, the plurality of conveyance guide units are arranged in a direction crossing the conveyance direction.
 5. The sheet conveyance apparatus comprising: a plurality of conveyance rollers which convey a sheet and which are arranged along a conveyance direction of the sheet; an elastic guide member which is fixed and supported at the central portion and both the ends of which serve as free ends facing an upstream side conveyance roller and a downstream side conveyance roller of the plurality of conveyance rollers, respectively; and the conveyed sheet is sandwiched between the conveyance roller and the elastic guide member, and the elastic guide member is elastically transformed to bring the sheet into press contact with the conveyance roller.
 6. The sheet conveyance apparatus according to claim 5, wherein the plurality of elastic guide members are arranged in an axial direction of the conveyance roller; and central portions of the plurality of elastic guide members are coupled to each other and integrated.
 7. An image reading apparatus comprising: a sheet conveyance apparatus according to claim 1; and an image reading unit which reads an image from a sheet conveyed by the sheet conveyance apparatus.
 8. A sheet conveyance apparatus comprising: a conveyance roller which has a shaft and a roller main body having an outer peripheral surface being in contact with a sheet, and which conveys the sheet; and a plurality of elastic guide members which are arranged on both the sides of the roller main body in an axial direction of the conveyance roller, which extend in a conveyance direction, and which can be elastically transformed, wherein the conveyed sheet is sandwiched between the conveyance roller and the plurality of elastic guide members which are elastically transformed, and elastic force of the elastic guide member brings the sheet into press contact with the outer peripheral surface of the roller main body. 